In:
Acta Physica Sinica, Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences, Vol. 71, No. 12 ( 2022), p. 127501-
Abstract:
Epitaxial FeGa/IrMn bilayers with exchange biases along the FeGa[100] and [110] directions are prepared on MgO(001) single crystal substrates by magnetron sputtering through controlling the orientation of the external field 〈i〉in situ〈/i〉 applied during growth. The effect of the exchange bias orientation on the magnetic switching process and the magnetic switching field are studied. The X-ray 〈i〉φ〈/i〉-scan indicates that the FeGa layer is epitaxially grown with a 45° in-plane rotation on the MgO(001) substrate along the FeGa(001)[110] direction and the MgO(001)[100] direction. The measurements of the angular dependence of the ferromagnetic resonance field and the corresponding fitting to the Kittel equation show that the samples have a superposition of fourfold symmetric magnetocrystalline anisotropy 〈inline-formula〉〈tex-math id="M4"〉\begin{document}$ {K}_{1} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M4.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M4.png"/〉〈/alternatives〉〈/inline-formula〉, unidirectional magnetic exchange bias anisotropy 〈inline-formula〉〈tex-math id="M5"〉\begin{document}$ {K}_{\mathrm{e}\mathrm{b}} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M5.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M5.png"/〉〈/alternatives〉〈/inline-formula〉, and uniaxial magnetic anisotropy 〈inline-formula〉〈tex-math id="M6"〉\begin{document}$ {K}_{\mathrm{u}} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M6.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M6.png"/〉〈/alternatives〉〈/inline-formula〉 with configuration of 〈inline-formula〉〈tex-math id="M7"〉\begin{document}$ {K}_{\mathrm{e}\mathrm{b}}//\left[100\right] $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M7.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M7.png"/〉〈/alternatives〉〈/inline-formula〉 or 〈inline-formula〉〈tex-math id="M8"〉\begin{document}$ {K}_{\mathrm{e}\mathrm{b}}//\left[110\right] $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M8.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M8.png"/〉〈/alternatives〉〈/inline-formula〉. The combined longitudinal and transverse magneto-optical Kerr effect measurements show that sample with 〈inline-formula〉〈tex-math id="M9"〉\begin{document}$ {K}_{\mathrm{e}\mathrm{b}}//\left[100\right] $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M9.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M9.png"/〉〈/alternatives〉〈/inline-formula〉 exhibits square loops, asymmetrically shaped loops, and one-sided two-step loops in different external magnetic field directions. In contrast, the sample with 〈inline-formula〉〈tex-math id="M10"〉\begin{document}$ {K}_{\mathrm{e}\mathrm{b}}//\left[110\right] $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M10.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M10.png"/〉〈/alternatives〉〈/inline-formula〉 exhibits one-sided two-step and two-sided two-step loops as the magnetic field orientation changes. Because the 〈inline-formula〉〈tex-math id="M11"〉\begin{document}$ {K}_{1} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M11.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M11.png"/〉〈/alternatives〉〈/inline-formula〉 is superimposed by 〈inline-formula〉〈tex-math id="M12"〉\begin{document}$ {K}_{\mathrm{u}} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M12.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M12.png"/〉〈/alternatives〉〈/inline-formula〉 and 〈inline-formula〉〈tex-math id="M13"〉\begin{document}$ {K}_{\mathrm{e}\mathrm{b}} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M13.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M13.png"/〉〈/alternatives〉〈/inline-formula〉, the in-plane fourfold symmetry of the magnetic anisotropy energy is broken. The local minima are no longer strictly along the in-plane 〈inline-formula〉〈tex-math id="M14"〉\begin{document}$ \left\langle{100}\right\rangle $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M14.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M14.png"/〉〈/alternatives〉〈/inline-formula〉 directions, but make a deviation angle which depends on the relative orientation and strength of magnetic anisotropy. A model based on the domain wall nucleation and propagation is proposed with considering the different orientations of 〈inline-formula〉〈tex-math id="M15"〉\begin{document}$ {K}_{\mathrm{e}\mathrm{b}} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M15.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M15.png"/〉〈/alternatives〉〈/inline-formula〉, which can nicely explain the change of the magnetic switching route with the magnetic field orientation and fit the angular dependence of the magnetic switching fields, indicating a significant change of domain wall nucleation energy as the orientation of 〈inline-formula〉〈tex-math id="M16"〉\begin{document}$ {K}_{\mathrm{e}\mathrm{b}} $\end{document}〈/tex-math〉〈alternatives〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M16.jpg"/〉〈graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20220166_M16.png"/〉〈/alternatives〉〈/inline-formula〉 changes.
Type of Medium:
Online Resource
ISSN:
1000-3290
,
1000-3290
DOI:
10.7498/aps.71.20220166
Language:
Unknown
Publisher:
Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences
Publication Date:
2022
